Different third generation 3G multimedia services have potential usage of a generic bootstrapping architecture GBA provided by the third generation partnership project 3GPP and being based on the authentication and key agreement AKA protocol to distribute subscriber certificates. These certificates are used by mobile operators to authenticate a subscriber before accessing the multimedia services and applications over a hypertext transfer protocol HTTP. The services and applications include presence (like an instant message system), video conferencing, messaging, video broadcasting, a push to talk application etc., and they are offered by IMS (IP, internet protocol, multi-media subsystem) operators. An infrastructure of the generic bootstrapping architecture also enables an application function in the network and on the user side to use shared keys. The GBA architecture has been enhanced by implementing a generic authentication architecture GAA to provide secure access over HTTP using a transport layer security TLS. GAA describes a generic architecture for peer authentication that can a priori serve for any present and future application. GM may also be described to be an authentication frame-work with an authentication reference model linking together GBA, security mechanisms, shared secret based and certificate based, and functional features.
Currently, however, it is not possible to have access authentication for a user using user equipment communicating in a first communications network accepting a first type of identification to a second communications network accepting a second type of identification with the first type of identification. This causes problems e.g. in the network management.